1. Field of the Invention
The present invention relates to a connector in a header of an implantable cardiac stimulator for coupling to a lead for conducting electrical signals between the cardiac stimulator and the heart.
2. Background Information
Implantable cardiac stimulators, including pacemakers, anti-tachycardia pacers, and defibrillators are used to artificially stimulate cardiac tissue with an electrical signal in order to correct or modify the rhythm of the heart. Implantable cardiac stimulators generally comprise a housing or can which hermetically encloses a battery and electronic circuitry for sensing electrical signals generated by the heart and for generating therapeutic electrical stimulating signals to be delivered to the heart. The housing is generally implanted subcutaneously. A lead having one or more electrodes at one end is implanted in the heart via an endovascular route so that the electrode is lodged in a selected chamber of the heart. The other end of the lead has a connector pin which is mechanically and electrically coupled to the cardiac stimulator.
It is important that the lead be safely secured to the cardiac stimulator to prevent it from being inadvertently decoupled. Since cardiac stimulators must be removed and replaced at the end of the useful life of the battery, preferably without disturbing the electrode, the lead connection must also be readily disconnectable.
It is known in the art to accomplish the connection by inserting an exposed connector pin of the lead into an electrical terminal located at the inboard end of a cylindrical bore in a header of the cardiac stimulator. The lead is then fixed in place by use of a setscrew, which extends through a hole in the side of the header and is received in a threaded hole in the electrical terminal. The setscrew is tightened until it bears against the side of the connector pin.
This conventional technique for securing the lead to the pacer has some disadvantages. The setscrew is extremely small and can be lost if it is inadvertently backed out too far. Also, the setscrew makes point contact with the connector pin of the lead, which can result in significant deformation of the connector pin if the set screw is over tightened, which can in turn make it difficult to disconnect the connector pin from the header of the cardiac stimulator.
It would be desirable to provide a connector in a cardiac stimulator for receiving a connector pin of a lead wherein the means for engaging the connector pin cannot be inadvertently lost. It would also be desirable to provide such a connector that is configured to alleviate the problem of deformation of the connector pin. These and other desirable goals are achieved by the present invention.